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No. 622,329. Patented A r. 4, I899. F. H. CRAFTS.

SPEED CHANGING DRIVING MECHANISM FOR LATHE-S.

(Application filed May 5, 1898.) (N o M o d e I.)

7122 wigs:

NITED "STATES.

PATENT OFFICE.

FRANCIS H. CRAFTS, OF BUFFALO, NEW YORK, ASSIGNOR TO THE CRAFTS MACHINE AND TOOL COMPANY, OF SAME PLACE.

SPEED-CHANGING DRIVING MECHANISM FOR LATHES.

srncxrrcnrxon forming part of Letters Patent No. 622,329, dated Aprn 4, 1899.

Application filed May 5, 1898. Serial No. 6791748. (N0 m del) To all whom it may concern.-

Be it known that I, FRANCIS H. CRAFTS, a citizen of the United States, residing at Buffalo, in the county of Erie and State of New York, have invented a new and useful Improvement in Speed-Changing Driving Mechanism for Lathes, 850., of which the following is a specification.

This invention relates to a driving mechanism for lathes and other machines in which it is necessary to change the speed of the ma- In the accompanying drawings, Figure 1 is a front view of my improved driving mechanism in connection with a lathe. Fig. 2 is a transverse vertical section thereof in line 2 2, Fig. 1. Fig. 3 is a view similar to Fig. 2, showing an overhead arrangement of the speedchanging mechanism. Fig. 4 is an enlarged fragmentary view of the belt-tightener shaft.

Like letters of reference refer to like parts in the several figures.

A is the rotary spindle of a lathe, and A an ordinary pulley secured thereto.

B is a horizontal main or line shaft preferably arranged below the fioor on which the lathe or other machine stands and supported in hangers C, secured to the joists or other supports. This main shaft may be driven by an electric motor mounted directly on the same or by a belt running around a drivingpulley D, mounted on the shaft. In addition to the pulley D the main shaft is provided with a series of different-sized pulleys D D D D.

E is a counter-shaft supported in the hangers C below and parallel with the main shaft B and carrying a series of different-sized pulleys E E E E, which correspond to the pul- Sueh a variable-speed drivleys D D D D of the main shaft, but are arranged in the reverse order, as shown.

F F F F are loose independent drivingbelts which pass around the several pairs of corresponding pulleys on the main and counter shafts Band E, so that upon tightening any one of these belts the counter-shaft is driven from the main shaft at a speed proportionate to the relative sizes of the two active pulleys, while the other loose belts remain idle on their pulleys. The lathe-spindle is driven from the counter-shaft E by a single belt G, running around the pulley A of the spindle and a pulley H, secured to the counter-shaft.

Each of the loose speed-changing belts F F F F is provided with an individual or independent tightener, which is preferably constructed as shown in the drawings. This tightener consists of a roller or small pulley a, j ournaled on the inner bifurcated arm of an upright bell-crank lover I, which is pivoted upon a horizontal rodor shaft J, supported on brackets j, projecting forwardly from the shaft-hangers C. The outer arm 11 of the bellcrank lever is connected with an operating or pull rod is, extending upwardly through the floor and through a suitable standard K,

the rod terminating in a suitable handle, as shown. Upon pulling this rod upward the inner arm of the bell crank lever is swung.

toward the opposing belt, forcing its roller against the belt and tightening the same, so as to transmit motion from the main shaft B to the counter-shaft E.

Z is a spring, perferably a torsion-spring, which tends constantly to swing the bell-crank lever and its roller away from the belt, so as toleave the same slack. This spring is coiled about the rod J and secured at one end to a collar 1, fixed to the rod, and at its other end to one of the perforated eyes or earsforming the hub of the lever, as shown in Figs. 1 and 4E. The several bell-crank levers are mount- .ed' side by side on the rod J, and each is provided with an individual retracting-spring Z.

m represents detent-pawls or dogs whereby the bell-crank levers I are locked in their operative position and which are adapted to engage, respectively, with toothed or ratchet segments 71,, arranged on the bell-crank levers connected at its ends with the shaft and the adjacent shaft-bearing, respectively. This spring may be of any other suitable construction, if desired, or any equivalent device may be used in place thereof. The rock-shaft 0 is provided at one end with an actuating-arm p, with which is connected an operating-rod 11 This rod extends upwardly through the iloor and terminates in a knob or treadle 19 hen one of the bell-crank levers is locked by its corresponding detent-pawl and it is desired to release the same for slackening the belt, the operator of the lathe or other ma chine simply depresses the operating-rod p of the rock-shaft, which causes the latter to turn in the proper direction to swing the detent upward out of engagement with the toothed segment of the bell-crank lever. As soon as the lever is unlocked it is swung away from the belt by its spring Z, as hereinbefore described. The rock-shaft also serves as a stop for limiting the outward movement of the belt-tighteners, the levers of the latter being provided for this purpose with lugs or projeetions g, which strike against the rock-shaft when the tighteners are unlocked.

The machine is thrown into gear with the main driving-shaft by tightening one or another of the slack belts by raising the proper operating-rod k, and when it is desired to change the speed the tightener which is in use is thrown off and the proper tightener is applied, thus changing the speed almost instantly and without shifting the belt which leads to the lathe-spindle and saving the time and avoiding the danger incident to shifting the belt.

The pressure of the belt-tightene'r can be readily regulated according to the character of the work under treatment, the belt being tensioned less for a light out and more for a heavy cut. The toothed segments of the bellcrank levers I and the detent-pawls m permit the tighteners to be locked in any position for maintaining the desired tension of the belt.

By driving the lathe or other machine from the counter-shaft bya single belt and arranging the counter-shaft and main shaft as shown the number of bolts and pulleys is materially reduced and the cost of the driving mechanism correspondingly lessened.

My improved driving mechanism is especially adapted for driving a large number of machines from a continuous main shaft arranged either overhead or below the floor, in which case the machines are placed in line with each other or in a single row, and each machine is provided with its own countershaft and speed-changing belts, pulleys, and tighteners. When the machines are driven from below the floor, which is the preferred arrangement, the downward pull of the drivin g-beltcounteracts the upthrust of the lathe, tool, placing the spindle nearly in balance. All strain is also removed from the top of the headstock, thus avoiding chatter-marks and obtaining a better class of work.

In the drawings four speed-changing belts and sets of pulleys are shown, giving a corresponding number of changes in speed; but a greater or less number may be employed, as may be desired.

When the variable-speed driving mechanism is employed overhead, as shown in Fig. 3, the counter-shaft E is arranged between the driven machine and the main shaft 13. The arrangement of the belt-tighteners is the same asin that first described; but the operating-rods of the first construction are replaced by cords k, which pass upwardly and downwardly around guide-pulleys journaled in hangers secured to the ceiling or joists, these cords terminating in convenient reach of the operator of the lathe or other machine. The rock-shaft carrying the detentpawls is in this case operated by a cord 1), depending from the arm of the rock-shaft.

I claim as my invention 1. The combination with a main and a counter shaft each carryinga pulley, of a belt running loosely around said pulleys, a tightcnerlever carryinga roller adapted to bear against said belt, an operating device for moving the lever to tighten the belt, a locking device for holding the lever in its operative position,- and a spring arranged to move the lever and its roller away from the belt when the lever is released from said locking device, substantially as set forth.

2. The combination with a main and a co unter shaft each carrying a pulley, of a belt running loosely around said pulleys, a tightenerlever carryinga roller adapted to bear against said belt, an operating device for moving the lever to tighten the belt, a spring tending to move the lever and its roller away from the belt, a detent for locking the lever in its 0perative position, and a releasing device for unlocking said detent, substantially as set forth.

3. The combination with a main and a counter shaft each carrying a pulley, of abelt running loosely around said pulleys, a tightener- 'lever having locking-teeth and carrying a roller adapted to bear against said belt, and a rock-shaft having a detent adapted to interlock with said teeth, substantially as set forth.

4:. The combination with a main and a counter shaft each carrying apulley, of abelt running loosely around said pulleys, a tightenerlever having locking-teeth and carrying a roller adapted to bear against said belt, a spring tending to swing said lever away from said belt, a rock-shaft having an operatinglever to tighten the belt, a spring tending to move the lever and its roller away from the belt, and a rock-shaft which is arranged in rear of said tightener-lever and forms a stop 15 for limiting the rearward swing of the lever and which carries a detent-pawl adapted to interlock with said lever, substantially as set forth.

Witness myhand this 31st day of March, 1898.

FRANCIS I-l. CRAFTS;

Witnesses:

CARL F. GEYER, KATHRYN ELMORE. 

